feat(ui/templates): derived-template action and slimmer composition row

Right-click a template now offers "New Derived Template" — opens
TemplateCreate with the parent pre-selected via a new ?parentId query
parameter. Composition rows in the tree drop the trailing
"→ TargetName" muted text; the kind glyph plus the instance name carry
enough meaning, and the composed template is one click away from the
row's right-click menu.

docs/plans/2026-05-11-templates-folder-hierarchy-design.md

@@ -29,7 +29,7 @@ Inheritance is **not** rendered as tree nesting in the image, and it is not rend
 | Root-level templates | Allowed (`FolderId` nullable). Existing templates migrate with `FolderId = null`. |
 | Folder delete with contents | Blocked; structured error lists child counts. |
 | Page layout | **Tree browser only** — no split-pane editor. Selecting a template navigates to `/design/templates/{id}` (TemplateEdit page); creating navigates to `/design/templates/create`. |
-| Tree node visuals | Per `Component-TreeView.md` Visual Design Guide V7: Bootstrap Icons (`bi-folder` / `bi-folder2-open` / `bi-file-earmark-text` / `bi-arrow-return-right`), name-only labels (no count/inherit badges on template nodes), folder child-count pill, composition `→ $Target` muted secondary text. |
+| Tree node visuals | Per `Component-TreeView.md` Visual Design Guide V7: Bootstrap Icons (`bi-folder` / `bi-folder2-open` / `bi-file-earmark-text` / `bi-arrow-return-right`), name-only labels (no count/inherit badges on template nodes; composition rows also name-only — the glyph signals the kind), folder child-count pill. |
 
 ## Data model
 
@@ -144,7 +144,7 @@ private record TmplNode(
 **Inline node labels** (see `Component-TreeView.md` V7 for the canonical recipe):
 - Folder: `<i class="bi bi-folder">` (closed) or `<i class="bi bi-folder2-open">` (expanded) + name (semibold when has children) + count-pill badge of direct children.
 - Template: `<i class="bi bi-file-earmark-text">` + `$Name` (semibold when has compositions). **No** inheritance hint, **no** attr/alarm/script count, **no** composition count on the node.
-- Composition: `<i class="bi bi-arrow-return-right">` + composition instance name + muted `→ $ComposedTemplateName` secondary text.
+- Composition: `<i class="bi bi-arrow-return-right">` + composition instance name only. The composed template name is intentionally omitted from the tree — open the owning template's edit page to see/manage compositions.
 
 **Search/filter:** out of scope for v1; the underlying component supports external filtering (per `Component-TreeView.md` R8) so it can be added later without component changes.
 
@@ -160,8 +160,8 @@ private record TmplNode(
 | ▶ 📁 _Default Templates                    |
 | ▼ 📂 Dev                                   |
 |     📄 $TestMachine                        |
-|        ↪ DelmiaReceiver → $DelmiaSvc       |
-|        ↪ MESReceiver   → $MesSvc           |
+|        ↪ DelmiaReceiver                    |
+|        ↪ MESReceiver                       |
 |     📄 $TestObject                         |
 | ▶ 📁 System                                |
 | 📄 $UnfiledTemplate                        |